Isaac Allerton was a Separatist passenger on the Mayflower.  Recent discoveries, soon to be published, show that Isaac was almost certainly the son of Bartholomew and Mary Allerton of East Bergholt, Suffolk. Isaac was a Blacksmith of London and Bartholomew a tailor of Ipswich, Suffolk.  He was a signatory to the Mayflower Compact.

He boarded the Mayflower with his first wife Mary Norris, their three living children, and his apprentice, John Hooke.  His sister Sarah married a fellow Mayflower passenger, Degory Priest.  Around 1626 he married his second wife, Fear, who was the daughter of passenger William Brewster. They had two children. He later married a third wife, Joanna Swinnerton, in New Haven, where he died in 1659.
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He was chosen as assistant to Governor Bradford in 1621, and continued in that capacity well into the 1630s.  He was sent to handle most of the buyout negotiations with the London investors that began in 1627, and continued through the early 1630s.  Members of the colony became dissatisfied with how he managed the finances of the colony, increasing debt and mixing his own business with the colony's finances. He was eventually banished from the colony for his unscrupulous dealings, going on to live in Marblehead, New Amsterdam, and New Haven.  He later became a well-to-do businessman elsewhere and in his later years resided in Connecticut.